NTS (Number Translation Services) is a domain of switched voice/data network telecommunications services wherein the dialed telephone number does not necessarily represent the physical number at which a call terminates. In other words, the dialed number is virtual as opposed to real. Virtual numbers must be translated into real numbers before network routing can take place, hence the domain's name. Well-known examples of NTS are 800 and 900 Services. Each of these services has its own 7-digit Open (i.e., not Private) Numbering Plan. Each active number in the Numbering Plan is the address of a customer record, which in turn contains the customer's profile. An important element of the profile is the real terminating number.
With a conventional call, where the dialed number is real, a network switch can perform network routing by analyzing the first 3 or 6 digits (i.e., NXX or NPA+NXX). NXX refers to the fourth to sixth digits of a 10-digit PSTN number (i.e., NPA+NXX+XXXX). The "N" digit is any value 2-9 and each of the "X" digits is any value 0-9.
Because these digits identify geographical areas of the network, the call can simply be forwarded to a switch that is closer to (or at) the destination. On the other hand, if a virtual number is encountered, the only way of knowing where to route the call is to consult a database that contains the virtual numbers and their corresponding real numbers.
Initially, when services such as 800 Service had low penetration, and thus few numbers in their Numbering Plans, it was acceptable to maintain an internal database within each switch. Then, as the quantity of numbers increased, it became necessary to consolidate all the databases into a single entity (replicated for network survivability) called the SCP (Service Control Point).
NTS that are based on unique access codes such as 800 and 900 have been around for many years. Recently, however, there has been growing pressure to introduce NTS to the basic PSTN (Public Switched Telephone Network). This pressure has come from several sources: i) business customers wanting to own their local telephone numbers, and hence lobbying for local number portability; ii) business customers wanting local NTS feature functionality such as Universal Access Number (i.e., having the same local telephone number provide access to many terminating locations) and time-dependent routing; iii) personal number mobility requirements, giving wired networks cellular-like roaming capabilities; and iv) the need to reduce telephone companies operating expense associated with conventional moves and changes. The result is expected to be a burgeoning demand for new access codes based on existing 3 and 6-digit prefixes, and hence many more Numbering Plans.
Another major growth area for NTS involves VPN (Virtual Private Networks). With VPN, business customers are able to establish personalized networks that share switch and transport resources with the PSTN. This is a far more cost-effective approach than having stand-alone physical networks with resources devoted entirely to individual customers. However, it is inherent to VPN that each customer have a unique Private Numbering Plan, such that the abbreviated in-house numbers can be translated into actual PSTN terminations.
Yet another growth area pertains to FX (Foreign Exchange) service, which is one of the most popular business long-distance services. This service involves customers who subscribe to telephone service in distant cities--i.e., in foreign telephone exchanges. The traditional approach has been to extend a very long, dedicated, physical telephone line from the distant city to the customer's remote premises. However, with the use of service-specific Numbering Plans for incoming and outgoing calls, it becomes possible for FX customers to be served from the nearest telephone office, thereby sharing the PSTN resources and eliminating the need for long, costly, dedicated telephone lines.
The phenomenal growth in NTS applications, sparked by the trends highlighted above, is expected to fuel a correspondingly phenomenal demand for new Numbering Plans, both Open and Private. Moreover, because the scope of NTS is expanding horizontally rather than vertically, and also down market from large business customers to basic POTS customers, demand to increase the power of the feature superset is expected to have a relatively low priority. These observations suggests that the ideal service creation environment is one that facilitates replication of a basic set of functionality in new Numbering Plans in the shortest possible time. This is contrary to the conventional service creation approach which focuses almost entirely on creating new services through enhancement of the feature set.
Traditionally, major new Intelligent Network services have been built as entirely new applications, especially when they have been associated with new Numbering Plans. Moreover, these applications have generally been deployed on different sets of SCP processors, if not completely separate SCPs. This has resulted in the same or very similar service logic being created over and over again, albeit through the use of library functions intended to facilitate service logic replication. Thus, the principal disadvantages of the traditional service creation methods are higher deployment cost, reduced network efficiency, wasted development effort, and longer time to market for the services.
Service creation schemes featuring service logic modules that can be structured randomly into tree-like structures are in widespread use under various trade names. In general, these schemes generate logic trees (called "decision graphs" or "call processing records", etc.) through work stations that incorporate high-level graphical programming languages and feature the use of "palettes", "icons", and other abstractions. The design intent of these schemes is service creation through additions to the feature set, and they are generally aimed at satisfying the needs of an entire service as a single entity.
On the other hand, with the advent of virtual telephone numbers, the interaction with terminating features that identify callers, must not be affected. For example, Caller Identifier, Call Return and other features of this type need to provide the called party with a number that can be returned to reach the caller. With the phasing out of physical or real numbers, and their subsequent irrelevance to customers, the number recorded must be the caller's virtual number. Accordingly, a solution is required to deal with this potentially undesirable interaction.
A need therefore exists for providing a new SCP platform which reduces the above shortcomings.
Accordingly, it is an object of the present invention to provide a new SCP platform capable of simultaneously handling a large number of completely independent 7-digit open numbering plans and 4-digit private numbering plans.
Another object of the present invention is to provide a new SCP platform with a data configuration which forms a matrix with numbering plans on one axis and service features on another axis.
Another object of the present invention is to provide an NTS matrix wherein service-specific memory addressing ranges corresponding to numbering plans are assigned.
Another object of the present invention is to provide an NTS matrix wherein service-specific search keys are used within each numbering plan to enable number translation.
Another object of the present invention is to provide an NTS matrix wherein each numbering plan in the matrix shares a common service logic tree and common reference library, capable of being pruned down to match the service logic needs of individual numbering plans.
Yet another object of the present invention is to provide in combination with the NTS matrix, a companion criss-cross numbering plan table, such that a look-up therein, using the real number of the calling party, will yield the virtual one.
In accordance with an embodiment of the present invention, there is provided in a telephone network having a number of telephone switching offices equipped with SSPs (Service Switching Points) operating with AIN (Advanced Intelligent Network) application software, and a remotely located SCP (Service Control Point) adapted to receive SS7 (Signaling System 7) messages from the SSPs, a method of translating a dialed number at the SCP to enable the routing of a call on the telephone network, comprising the steps of:
receiving at a first SSP a number of digits sent from a calling station;
identifying an access code from the received digits using the SSP's IN trigger;
formulating an SS7 message appropriate to the IN trigger used;
transmitting the SS7 message from the first SSP to the remotely located SCP via a CCS (Common Channel Signaling) transport facility;
pre-translating at the SCP the received SS7 message to determine the appropriate numbering plan and an assigned search key;
identifying, using the assigned search key, within the determined numbering plan a routing number;
formulating another SS7 message at the SCP containing the routing number; and
transmitting the formulated SS7 message to the first SSP to instruct the telephone network how the complete the call.
In accordance with another embodiment of the present invention, there is provided in a telephone network having a number of telephone switching offices equipped with SSPs (Service Switching Points) operating with AIN (Advanced Intelligent Network) application software, and a remotely located SCP (Service Control Point) adapted to receive SS7 (Signaling System 7) messages from the SSPs and translate a dialed number to enable the routing of a call on the telephone network, the SSP having means for identifying an access code from the received digits using a IN trigger and means for formulating an SS7 message appropriate to the IN trigger used and means for transmitting the SS7 message from the SSP to the remotely located SCP via a CCS (Common Channel Signaling) transport facility, the SCP being comprised of:
means for pre-translating the received SS7 message to determine the appropriate numbering plan and an assigned search key;
means for identifying, using the assigned search key, within the determined numbering plan a routing number;
means for formulating another SS7 message containing the routing number; and
means for transmitting the formulated SS7 message to the SSP to instruct the telephone network how the complete the call.